Of the many raw materials used by the paper and textile industries, cellulose fibers have occupied the dominant position for many years. The techniques of paper making are known worldwide and the basic principles have not changed. Despite great improvements in papermaking, however, procedures for strengthening cellulose fibers in the papermaking process are often expensive, time consuming, and environmentally questionable.
The kraft or sulfate process is probably the most extensively employed method to produce strong cellulose fibers. The active ingredients in pulping wood to its fibrous state are sodium hydroxide and sodium sulfide, in a strong alkaline solution. The process generates objectionable smells from the sodium sulfide produced during the process. Kraft pulps are dark in color, difficult to bleach and very strong.
Nevertheless, cellulose fibers obtained from the pulping process are generally unsuited for paper making and must first be refined. With given pulps, final paper properties are largely controlled by the type and extent of refining action employed. A variety of additive materials can be introduced to the paper-making pulps, commonly called "furnish", during stock preparation. Fillers such as clays, or calcium carbonate are used for the control of sheet opacity and for other reasons. Dyes are used extensively for color control and other additives such as wet-strength agents, and defoamers are used as needed.
For the most part, however, operations designed to increase the strength and/or other physical properties of paper take place subsequent to the paper making operation and are called "off-machine converting." These converting operations are highly complex and include embossing, coating, waxing, laminating, impregnating, saturating, currogating, and printing. For example, food packaging has led to extensive paper utilization with the paper often being coated, waxed, resin-impregnated, or combined with other foils and films. A relatively simple and inexpensive method of improving the paper making process and increasing the stiffness and ultimate strength of paper is needed.
In textile making processes, cotton fibers which are essentially pure cellulose are typically formed first into yarns or threads which are in turn used in waving or non-woven processes to form fabrics or other textile materials. Prior to and during its formation into yarns, threads or otherwise, raw cotton materials are subjected to various processes such as washing, opening, carding, drawing, combing, spinning and other processes well known in the textile making industry. Similar to The paper industry, processes designed to treat raw cotton fibers or articles such as fabric sheets made therefrom are typically complex, expensive and environmentally questionable.